Wi-Fi Calling with iOS8 and T-Mobile

I was sitting at home watching an Apple oriented video podcast that was discussing how Wi-Fi calling was now available in iOS 8 and that T-Mobile was one of the first carriers rolling this out. I realized that this may help me specifically with some of the dropped call issues I had been experiencing. I then grew curious, T-Mobile was offering a ‘customized’ router to subscribers that professed to offer home users better connectivity than their current gear. How did that work I wondered. With that I set about finding out by switching on Wi-Fi calling in my phone and doing some packet captures with the handy Remote Sniffer provided in my home Aerohive AP-370.

First of all I investigated how Wi-Fi calling actually worked. Digging around on the Internet turned up that it was a form of GAN/UMA that T-Mobile was using. Essentially this sends packets that would normally be sent over the GSM network via the Internet. With a bit more digging, however, I discovered on Reddit that T-Mobile used to use UMA but are now deploying IMS. The essential point for WLAN engineers such as myself is that we now have encrypted voice traffic going over our networks to the Internet which route to whichever provider is allowing their subscribers to use this service. As an aside, this isn’t a new thing as T-Mobile has been doing it since 2007 for Android phones.

Wi-Fi Calling Capture

So lets break down what’s going on here. T-Mobile being focused on the home use case is providing a high end router to customers which essentially provides QoS enabled connectivity so voice packets from their phones using Wi-Fi calling are prioritized properly for home users. That’s a win for them in that they will get great voice calls from their phones on their new router. What happens when those same users bring their phone into work and connect to the enterprise WLAN cause their office ‘just never had good cell reception’? Now we have a lot more devices doing what looks like ESP encrypted traffic that has voice priority (6) set on the packets.

Wi-Fi Calling QoS Capture

I would say as a WLAN designer, you should be taking into account that a lot of BYOD devices, specifically phones, will mean an increase in voice traffic on both your WLAN and the rest of your LAN. Read up on how it works at my pal Andrew’s blog, Revolution WiFi. I especially recommend his series of posts on Voice-Enterprise and Roaming.

The Internet of Cycling ‘IoC’ or Bike Area Networks

My good buddy, Devin Akin in a blog over at AirTight Networks has kicked off a discussion about a subject that is both over-hyped and under-hyped at the same time, the so called Internet of Things. Over-hyped because there are a lot of people running around breathlessly talking about how its going to change everything in the world and under-hyped because it’s actual real-world impact is going to be a lot more significant than we think. At least in my little corner of the security world. The way I’m going to emphasize this is by describing a bunch of ‘things’ related to one of my favorite activities cycling (BTW, that link is a very interesting article on cycling, you should go read it, seriously).

Back from a great day's riding

To give a little bit of history, I’ve been an avid cyclist since I was a very small scrawny kid and I made a deal with my mum to get a new ten speed where I saved up half the money from doing a paper run and she supplied the other half. I loved it Even into adulthood, I cycled every chance I could. I moved to Switzerland and cycled to and from work, to the UK, same, basically everywhere I could get my hands on a bike and the space to do it, I chose to cycle. This changed when I moved to the US in 1996 because I landed in Los Angeles. This city is one of the few that I have lived in which has a complete, unabashed love of the car. They built huge freeways just to prove it and celebrated going fast on them. What they didn’t build was places for cyclists and I had to drive long distances to get to work. I still had a mountain bike, which I rode when I could on trails away from the streets as much as possible, but I was not able to do it often as I wanted to.

My noble steed

After moving to Denver, I spent a good few years on the road almost constantly and during that purchased the above bike which I rode much less than I wanted to because, well, excuses. I one day had a wake up in that I discovered I was becoming decidedly unfit from to many years of eating well and not exercising well so I made a decision to change that. My way of doing that was to go back to something I know I loved to do and that to me felt natural, cycling to work each day. It was easy to incorporate into my daily routine as I was spending a lot of time working in a downtown Denver office now plus, no more excuses.

One thing that has really changed a lot about cycling now from when I did it a lot before moving to the USA is that now there are so many gadgets that can do things and tell you things about your cycling to keep your interest and enthusiasm up. I haven’t by any means purchased a lot of things, but I have a heart rate strap, speed and cadence meter which all connect via bluetooth to my phone which itself outputs what’s going on to a display built for that purpose. This is what the internet of things is about, giving you access to a whole lot of information you previously didn’t get from something you have or do and giving you the ability to use it in new ways. For me now, I can track my health while cycling, tweet messages to friends about how far I’ve ridden (automatically, as I’m riding) compile multiple statistics about my rides combining GPS and other data and uploading it to sites like Strava or RideWithGPS. This is great stuff and really lets me scratch my geeky itch about cycling.

To continue this a little more, I’m going to do a bit of speculating as to how this could advance even more in the future. You can criticize me later as to which come true and which never will. I can see bike riding as becoming more a ‘bike area network’ of sensors and various wireless devices. These devices, much as cars are beginning to, will talk to other riders, exchanging information as we ride, giving us useful feedback about what parts of the ride are congested and perhaps even giving us realtime mapping of different routes with travel times. I can see the bike detecting a possible blowout of a tire and flashing a warning, giving maintenance information that the chain needs oiling or even just more advanced monitoring of the rider’s health without anything more than putting your hands on the handlebars. The thing is, all this information won’t just stay in the rider’s phone or bike, it will be automatically and constantly uploaded to the internet with a minimal amount of effort.

I know what you’re thinking, people won’t want to do that, but people already do things like this all the time that take more effort, such as manually uploading data from their ride to Strava for all to see. If the manufacturers of the bikes and devices that do this make it easy and convenient for people, they’ll do it just to show other people what they are up to. The security issues here start as soon as people start to believe they can make money of hacking into those systems. Sure, Joe Blog’s ride and health data might be meaningless to anyone but himself and his ride buddies, but you can say that about a lot of data out there on the internet today that gets stolen from highly public servers. If someone is more important as well, perhaps Joe’s CEO who happens to ride with him, then the data gets even more interesting to nefarious types.

This is to me the next logical step beyond the wireless networks users are demanding at work. They will eventually want to be connected everywhere and with everything they can think of and use that data in new an unique ways to enhance their lives. Even if I just think about how much I’ve gotten from the few simple gadgets I have on my bike now, with an internet connection and see that we are really just getting going with it now, I believe there will be some amazing things that will arrive with the Internet of Things. The thing is, where there is a load of money to be made, there will be also a lot of people out there trying to steal a bit of it for themselves. That’s what is going to keep me busy and working for many years to come. Now perhaps I’ll just go off and patent ‘bike area networks’ while I still can.

Meeting old friends and making new one’s at the Wireless LAN Professional’s Conference


I’m on my way home after spending several days with about 100 friends. Some were new friends, I met them for the first time this week as they had decided to come to the WLPC. Some were friend’s I’d known on social media for a while but never met in person. And some were old friends I’ve known for some time through being an active part of the WLAN community. This to me is one of the reasons I love my job and my career, there are so many talented and good people that I have gotten to know through doing it and I really have a blast getting to expand my circle of friends in this industry.

I must say that Keith Parsons really made his dream come true of putting on an amazing conference and I thank him for giving me the opportunity to be one of the speakers. I spoke (of course) on WLAN Security and I was a little anxious just before speaking mainly because I wasn’t sure how many people would come to listen. I believed that VP Ketonen would draw more people to his talk as it was on advanced WLAN performance analysis, which was running at the same time as mine. I was relieved to see that the room was full with a good number of people waiting to hear what I was going to say. I felt comfortable for two reasons, first it’s a subject I know how to speak about and that I have quite a few opinions on, second here was a room full of friends that I knew and felt relaxed around. So really all I needed to do was speak up and give my opinions about where I thought WLAN security is today.

Still the feeling afterwards of having people come up to me to say ‘good job’, seeing tweets from people agreeing with something I said or the nods in the audience when I went into a particular topic and the interested questions that came from the audience was really something that made me think, wow! I had another wow moment a bit later when Peter Thornycroft, in his closing talk mentioned something I had said and agreed with me. It’s a wonderful feeling to have your peers validate your opinions and thoughts on a subject. I would highly recommend any of the attendees who feel they have something to say to sign up as a speaker at the next WLPC.

Finally some thoughts on the sessions I attended during the conference. I found several times I had much difficulty picking which one to go to and I am glad that Keith had them all recorded so I can go back and see what I missed. I know all my friends who were presenting did an amazing job as well putting across their passion for wireless and sharing the knowledge that they have with the other attendees there. To all of you I say ‘great job, you did a fantastic thing presenting and sharing the information you have’. I can’t wait to see all my friends again.